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American Astronomical Society, Astrophysical Journal, 1(576), p. 533-551, 2002

DOI: 10.1086/341539

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A Flux‐Tube Tectonics Model for Solar Coronal Heating Driven by the Magnetic Carpet

Journal article published in 2002 by Eric R. Priest ORCID, Jean F. Heyvaerts, Alan M. Title, Others
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

We explore some of the consequences of the magnetic carpet for coronal heating. Observations show that most of the magnetic flux in the quiet Sun emerges as ephemeral regions and then quickly migrates to super-granule boundaries. The original ephemeral concentrations fragment, merge, and cancel over a time period of 10–40 hr. Since the network photospheric flux is likely to be concentrated in units of 10 17 Mx or smaller, there will be myriads of coronal separatrix surfaces caused by the highly fragmented photospheric magnetic configuration in the quiet network. We suggest that the formation and dissipation of current sheets along these separatrices are an important contribution to coronal heating. The dissipation of energy along sharp boundaries we call, by analogy with geophysical plate tectonics, the tectonics model of coronal heating. Simi-lar to the case on Earth, the relative motions of the photospheric sources will drive the formation and dissipa-tion of current sheets along a hierarchy of such separatrix surfaces at internal dislocations in the corona. In our preliminary assessment of such dissipation we find that the heating is fairly uniform along the separa-trices, so that each elementary coronal flux tube is heated uniformly. However, 95% of the photospheric flux closes low down in the magnetic carpet and the remaining 5% forms large-scale connections, so the magnetic carpet will be heated more effectively than the large-scale corona. This suggests that unresolved observations of coronal loops should exhibit enhanced heating near their feet in the carpet, while the upper parts of large-scale loops should be heated rather uniformly but less strongly.